Truck drivers and deliverymen have a significant, 30% increased risk of bladder cancer. Analysis of occupational data from the National Bladder Cancer Study has indicated an increased risk of bladder cancer among painters, regardless of the type of painter. The incidence of pleural mesothelioma is 8 times higher than peritoneal mesothelioma among males but just over twice as high among females. For white males, incidence of pleural mesothelioma increased significantly over the 8 year time period 1973-1980. Among white males, lung cancer incidence rates increased more than 200% from the late 1940s to 1979-80; the corresponding increase among white females was greater than 250%. Rates continue to increase among the older age groups. Among the younger groups, the rates of increase are diminishing and some decreases in rates are apparent among males. Strong significant inverse trends between lung cancer incidence and both income and education were apparent among both white and black males, and the effect of income exceeded that of education. Significant leukemia excesses were observed following chemotherapy for breast cancer, ovarian cancer, and multiple myeloma. Patients treated with radiation, but without chemotherapy, were also found to be at increased risk of second leukemias for uterine corpus cancer. A statistically significant positive association with respect to stage of a first and second breast cancer was found. This finding is consistent with an immunological hypothesis regarding the effect of cell mediated immunity associated with a first breast cancer on second breast cancer behavior. Continued improvement in survival for Hodgkin's disease patients diagnosed in the 1970s in 9 areas covered by the NCI's SEER Program was observed. Between 1973-75 and 1976-77 3-year relative survival rates for whites increased significantly from 71 to 78%. Research in theoretical statistical modeling has led to a characterization of length bias at a prevalence screen in terms of screening parameters and disease natural history.